1. Field of the Invention
The present invention is generally in the field of electrical circuits and systems. More specifically, the present invention is in the field of voltage regulation in electrical circuits and systems.
2. Background Art
Voltage regulators are widely used in a variety of modern electronic devices and systems. Many integrated circuit (IC) applications, for example, require conversion of a DC input signal to a lower, or higher, DC output, in order to drive one or more circuit components. For example, a buck converter may be implemented as a voltage regulator to convert a higher voltage DC input to a lower voltage DC output for use in low voltage applications in which relatively large load currents are required.
One conventional approach to implementing a voltage regulator, such as a buck converter, for example, includes utilizing several power stages in a multi-phase arrangement. In that arrangement, each power stage is sequentially activated in a phase delayed manner by a control circuit of the voltage regulator, thereby distributing current production across the several output power stages. Because voltage regulators are increasingly called upon to provide stable voltage outputs to electronic systems, such as a microprocessor for example, having a wide range of current requirements, the ability to provide effective transient response is an important performance parameter of voltage regulators.
A conventional approach to providing transient response in a multi-phase voltage regulator includes using a feedback circuit with an error amplifier to compare the output voltage of the voltage regulator with a reference voltage. When the load demands on the voltage regulator require an increase in output, for example, the error amplifier may respond by increasing the power stage duty cycle in order to provide more energy to the output capacitors. However, this conventional approach suffers from several drawbacks.
One disadvantage of the conventional approach is latency owing to the delay between the occurrence of the load transient and the next phased switching pulse. In addition, the amount of energy transferred in a single switching pulse is typically inadequate to meet the output demands on the voltage regulator. As a result, the conventional approach typically relies on several output capacitors to store the energy necessary for effective transient response. As the transient requirements on voltage regulators become ever more stringent, progressively more output capacitors are required under the conventional arrangement. However, incorporation of additional output capacitors is expensive and inefficient, both in terms of monetary cost and the circuit area required for their implementation.
Thus, there is a need to overcome the drawbacks and deficiencies in the art. There is a need in the art, for example, for a voltage regulator that can provide a transient response meeting or exceeding transient requirements, while reducing the number of output capacitors compared to conventional voltage regulators providing a comparable transient response.